Enzymatic Separation of Cellulose and Polymers from Absorbent Articles
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Solution Overview
Problem
Current recycling methods for disposable absorbent articles, such as diapers, are inefficient and environmentally harmful due to the use of harsh chemicals and difficulty in separating superabsorbent polymers and cellulose fibers, leading to low purity and quantity of recovered materials.
Innovation Solution
A method involving shredding, re-pulping, and dehydration of disposable absorbent articles using sea water and calcium chloride to convert superabsorbent polymers from a gel state to their original form, followed by enzymatic processing with cellulase to release cellulose fibers from polymeric materials, resulting in clean streams of plastics and fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If harsh chemicals are used to separate materials in disposable absorbent articles, then separation efficiency improves, but environmental harm and processing cost increase
Solution Approach 1:
The patent changes the chemical parameters of the separation medium from harsh chemicals to a milder aqueous solution containing salt and enzyme. This parameter change maintains separation efficiency while reducing environmental harm, as the milder conditions achieve effective material separation without the need for strong chemicals that damage the environment.
Solution Approach 2:
The patent replaces harsh chemical separation with a combined mechanical and biological approach. Mechanical shredding breaks down the article structure, followed by enzymatic action that selectively degrades adhesives holding cellulosic fibers to polymers. This substitution eliminates the need for harsh chemicals while achieving effective separation.
2Quantity of substance
If superabsorbent polymers are allowed to remain swollen in gel state, then moisture absorption capacity is maintained, but mechanical separation becomes impossible
Solution Approach 1:
The patent applies preliminary dehydration to the superabsorbent polymers before mechanical separation. By removing excess moisture and converting the gel state to a drier state, the polymers become mechanically separable while retaining their moisture absorption capacity for subsequent use. This preliminary action resolves the contradiction between maintaining absorption capacity and enabling separation.
3Stability of the object's composition
If cellulosic fibers and polymers are mechanically mixed with adhesives, then uniform distribution is achieved, but separation into individual materials becomes difficult
Solution Approach 1:
The patent introduces an enzyme as an intermediary substance to facilitate separation. The enzyme specifically targets and degrades the adhesive bonds between cellulosic fibers and polymers, acting as a mediator that breaks the stable mixed structure. This allows efficient separation into individual materials while the uniform distribution achieved during manufacturing is preserved in the quality of the separated streams.
4Ease of operation
If disposable absorbent articles are incinerated or landfilled, then disposal is simplified, but processing cost and environmental impact increase
Solution Approach 1:
The patent implements a recovery system that extracts valuable materials (cellulosic fibers, polymers, superabsorbent polymers) from disposable absorbent articles through separation and dehydration processes. Instead of simple disposal, the materials are recovered and can be reused or recycled, eliminating the need for incineration or landfilling and reducing carbon dioxide emissions while maintaining operational simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the efficient and economical recovery of high-purity materials from disposable absorbent articles, reducing chemical usage and environmental impact while achieving nearly pure plastic and fiber streams for reuse.
Implementation Method 1
processing the mixed polymeric material and cellulosic fiber stream using an enzyme to release the cellulosic fibers from the polymeric materials
Implementation Method 2
dehydrating includes belching water from swollen superabsorbent polymers (SAPs) by immersing swollen SAP in a gel state into a composition for removing moisture, wherein sea water and 0.5 to 3% by weight of calcium chloride based on the weight of sea water are mixed
Data Source
Figure 1
AI summary
Improving the recovery from recycling a disposable absorbent article including superabsorbent polymer includes separating the article into a mixed polymeric material/cellulosic fiber stream and a superabsorbent polymer/fibers stream; and processing the mixed polymeric material/cellulosic fiber stream using an enzyme to release the cellulosic fibers from the polymeric materials. The method can also include shredding the disposable absorbent article; re-pulping the shredded disposable absorbent article; and dehydrating the superabsorbent polymer, wherein dehydrating includes belching fluid from swollen superabsorbent polymers (SAPs) by immersing swollen SAP in a gel state into a composition for removing moisture, wherein seawater and 0.5 to 3% by weight of calcium chloride based on the weight of seawater are mixed for 10 minutes to 4 hours.